Hood, W., 2021. zis a ba 4th-year Post-Restoration Tidal Marsh Monitoring Report. Skagit River System Cooperative, La Conner, WA. pp. 8.

The zis a ba tidal marsh restoration site is located in the Stillaguamish River Delta at the mouth
of the old Stillaguamish River. European-American settlement in the late 19th century converted most of
the Stillaguamish Delta from tidal marsh and floodplain swamp to agricultural use through the
construction of dikes to prevent tidal and riverine flooding and allow replacement of native vegetation
by agricultural crops. Since then, native populations of salmon have been in decline and Puget Sound
Chinook salmon have been listed as a threatened species. Because tidal marshes are critical rearing
habitat for juvenile Chinook salmon, there has been significant effort addressed to restoring historical
tidal marshes to recover Chinook salmon populations.
The 36.2-ha (approximately 90-acre) zis a ba restoration site was restored to tidal and riverine
flooding in 2017 through the removal of dikes around its water-ward perimeter. Additionally, seven
large tidal channels were excavated on the site in accordance with allometric predictions derived from
nearby reference tidal marshes (Hood 2016, 2018). Dike removal and channel construction were
hypothesized to be sufficient for allowing native vegetation recolonization of the site and for juvenile
Chinook salmon to occupy the excavated channels and benefit from primary and secondary production
on the site. The excavated channel networks were expected to develop new tributaries and to
potentially lengthen through tidal erosion, although the likely rate of this further channel development
was unknown. This report describes monitoring of tidal channel development and vegetation
colonization two and four years after site restoration through dike removal and channel excavation.